Techniques for controlling precursors in chemical deposition processes

ABSTRACT

An apparatus for controlling precursor flow. The apparatus may include a processor; and a memory unit coupled to the processor, including a flux control routine. The flux control routine may be operative on the processor to monitor the precursor flow and may include a flux calculation processor to determine a precursor flux value based upon a change in detected signal intensity received from a cell of a gas delivery system to deliver a precursor.

RELATED APPLICATIONS

This application is a continuation application to U.S. Non-Provisionalpatent application Ser. No. 15/946,483, filed Apr. 5, 2018, entitledTECHNIQUES FOR CONTROLLING PRECURSORS IN CHEMICAL DEPOSITION PROCESSESwhich claims priority to U.S. Provisional Patent Application No.62/611,645, filed Dec. 29, 2017, entitled TECHNIQUES FOR CONTROLLINGPRECURSORS IN CHEMICAL DEPOSITION PROCESSES, both of which applicationsare incorporated by reference herein in their entirety.

FIELD

The present embodiments relate to deposition processes, and moreparticularly, to control of precursors in chemical deposition processes.

BACKGROUND

In the present day, device fabrication, such as semiconductor devicefabrication may entail chemical deposition processes to form thin layerswith precise thickness control, including over three dimensionalstructures. Such chemical deposition processes include chemical vapordeposition (CVD) and atomic layer deposition (ALD), among otherprocesses.

Such chemical deposition processes may involve delivering precursorsfrom a solid source, gas source, or liquid source, such as an ampoule.For example, the precursor may be delivered from an ampoule to a processchamber, where the precursor reacts to form a layer or sub-layer on asubstrate. In present day apparatus, the amount of precursor beingdelivered may not be properly characterized, leading to variability indelivery of precursor substrate-to-substrate, ampoule-to-ampoule, orover the lifetime of an ampoule. Delay in detecting ampoule end of lifecan result in significant amount of wafer (substrate) discard. As aprecaution, users may track carrier gas flow through an ampoule and mayhalt the use of a precursor in an ampoule well before actual end oflife, resulting in a considerable portion of the ampoule fill beingunused, and causing higher overall cost.

With respect to these and other considerations the present disclosure isprovided.

SUMMARY

In one embodiment, an apparatus for controlling precursor flow mayinclude a processor, and a memory unit coupled to the processor,including a flux control routine. The flux control routine may beoperative on the processor to monitor the precursor flow. The fluxcontrol routine may include a flux calculation processor to determine aprecursor flux value based upon a change in detected signal intensityreceived from a cell of a gas delivery system to deliver a precursor.

In an additional embodiment, a method of controlling precursor flow mayinclude providing a flow of a precursor through a gas delivery system,measuring a change in detected signal intensity in a cell of the gasdelivery system, caused by the flow of the precursor, and determining aprecursor flux value based upon the change in detected signal intensity.

In another embodiment, an apparatus for controlling precursor flow mayinclude a source to output the precursor, and a sensor assembly,communicatively coupled to the source. The sensor assembly may include acell, coupled to the source, to receive and conduct the precursor, alight source, disposed on a first side of the cell, to transmit lightinto the cell, and a detector, disposed on a second side of the cell,opposite the light source, to detect light transmitted through the cell.The apparatus may also include a control system, the control systemarranged to determine a precursor flux value based upon a change indetected light intensity received from the cell during flow of theprecursor through the cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a system for chemical deposition, according to embodimentsof the disclosure;

FIG. 1B shows one embodiment of a control system of the system of FIG.1A;

FIG. 1C shows another system for chemical deposition, according toembodiments of the disclosure;

FIGS. 2A to 2B show operation of a sensor assembly according toembodiments of the disclosure;

FIGS. 3A and 3B illustrate exemplary signals collected by the sensorassembly of FIG. 2A;

FIG. 4 shows a graphical depiction of various outputs of a controlsystem, in accordance with embodiments of the disclosure;

FIG. 5 is a composite graph depicting precursor flux and integrated fluxover time, according to some embodiments;

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D are exemplary graphs thatillustrate the relationship between integrated flux or related entitiesand operating parameters of a system, in accordance with embodiments ofthe disclosure;

FIG. 7 illustrates integrated precursor flux behavior as a function oftime, with and without temperature compensation, in accordance withembodiments of the disclosure;

FIG. 8 presents an exemplary process flow according to embodiments ofthe disclosure;

FIG. 9A presents an exemplary process flow according to embodiments ofthe disclosure; and

FIG. 9B presents a model system according to embodiments of thedisclosure.

The drawings are not necessarily to scale. The drawings are merelyrepresentations, not intended to portray specific parameters of thedisclosure. The drawings are intended to depict exemplary embodiments ofthe disclosure, and therefore are not be considered as limiting inscope. In the drawings, like numbering represents like elements.

Furthermore, certain elements in some of the figures may be omitted, orillustrated not-to-scale, for illustrative clarity. The cross-sectionalviews may be in the form of “slices”, or “near-sighted” cross-sectionalviews, omitting certain background lines otherwise visible in a “true”cross-sectional view, for illustrative clarity. Furthermore, forclarity, some reference numbers may be omitted in certain drawings.

DETAILED DESCRIPTION

The present embodiments will now be described more fully hereinafterwith reference to the accompanying drawings, where some embodiments areshown. The subject matter of the present disclosure may be embodied inmany different forms and are not to be construed as limited to theembodiments set forth herein. These embodiments are provided so thisdisclosure will be thorough and complete, and will fully convey thescope of the subject matter to those skilled in the art. In thedrawings, like numbers refer to like elements throughout.

The embodiments described herein provide novel processing and control ofprecursors in chemical deposition processes, such as atomic layerdeposition (ALD) processes. ALD generally involves sequential exposureto two or more reactants to deposit a given monolayer of material. Invarious embodiments, a chemical deposition process may be performed todeposit any appropriate material, including oxides, nitride, carbides,dielectrics, semiconductors, or metal. The chemical deposition processmay involve control of precursor flow as detailed in the embodiments tofollow.

Turning now to FIG. 1A, there is shown a system 100 for chemicaldeposition, according to embodiments of the disclosure. The system 100involves use of at least one precursor, generally provided as a gaseousspecies to process chamber, referred to as deposition chamber 110. Thesystem 100 may be employed to perform chemical vapor deposition (CVD) oratomic layer deposition (ALD) in different embodiments. The embodimentsare not limited in this context. The system 100 includes a source, suchas ampoule 104, where the ampoule 104 may contain a solid, liquid orgas. The ampoule 104 may be maintained at an elevated temperature togenerate a gaseous species, which species may be referred to herein as aprecursor. The ampoule 104 may be coupled to a delivery system 114,configured to conduct at least one gaseous species, and in some cases,multiple gaseous species, to the deposition chamber 110, as in known CVDor ALD systems. For example, the delivery system 114 may include aplurality of gas lines, valves, and flow controllers. At least a portionof the delivery system 114 may be contained within a hot chamber 106,where the hot chamber 106 is maintained at an elevated temperature withrespect to the ampoule 104, ensuring precursor(s) remain in a gaseousstate, at least until entering deposition chamber 110.

The system 100 may further include a sensor assembly 108, arranged tomonitor flow of at least one precursor between the ampoule 104 anddeposition chamber 110. The sensor assembly 108 may be coupled to acontrol system 112, where the control system 112 may output informationor signals to a user, as well as send control signals for controllingoperating parameters of system 100, including temperature, precursorflow, and so forth. Details of an embodiment of the control system 112are shown in FIG. 1B and discussed further below.

In accordance with embodiments of the disclosure, the control system 112may be implemented in a combination of hardware and software. Thecontrol system 112 may comprise various hardware elements, softwareelements, or a combination of hardware/software. Examples of hardwareelements may include devices, logic devices, components, processors,microprocessors, circuits, processor circuits, circuit elements (e.g.,transistors, resistors, capacitors, inductors, and so forth), integratedcircuits, application specific integrated circuits (ASIC), andprogrammable logic devices (PLD). Examples of hardware elements may alsoinclude digital signal processors (DSP), field programmable gate array(FPGA), memory units, logic gates, registers, semiconductor device,chips, microchips, chip sets, and so forth. Examples of softwareelements may include software components, programs, applications,computer programs, application programs, system programs, softwaredevelopment programs, machine programs, operating system software,middleware, firmware, software modules, routines, subroutines, andfunctions. Examples of software elements may also include methods,procedures, software interfaces, application program interfaces (API),instruction sets, computing code, computer code, code segments, computercode segments, words, values, symbols, or any combination thereof.Determining whether an embodiment is implemented using hardware elementsand/or software elements may vary in accordance with any number offactors, such as desired computational rate, power levels, heattolerances, processing cycle budget, input data rates, output datarates, memory resources, data bus speeds and other design or performanceconstraints, as desired for a given implementation.

As an example, the control system 112 may include various hardwareoutputs, which outputs may be embodied as signals for controlling othercomponents of system 100, may be output on user interfaces, or output inother manner. In some examples, the hardware outputs may be employed asinputs by control system 112 to control components of system 100, asdetailed below. Table I includes a listing of exemplary hardware outputsaccording to some embodiments of the disclosure. In this example,temperature, such as temperature of the ampoule 104, may be output, aswell as gas pressure, precursor concentration, and a health monitor(reference signal).

TABLE I Output Temperature (C.) Pressure (T) Concentration (%) HealthMonitor (a.u.)

These outputs may be collected periodically, intermittently, and insynchronicity, or separately (in time) from one another.

Turning now to Table II. there are shown a set of operations orcapabilities where the capabilities may be performed by the controlsystem 112, according to some embodiments of the disclosure, where thesecapabilities are detailed in the discussion to follow.

TABLE II Capability Purpose Chamber Flux (umol/sec) Model for precursorflux delivered to wafer Integrated Ch. Flux (umol) Total precursor fluxover a wafer Ampoule Integrated flux Lifetime flux of precursor ampouleEnd of life Detection Signals ampoule change needed Fault detectionDetect and classify faults (e.g. clogs) Ampoule T compensation Feedbackloop for dynamic T adjust

Turning now to FIG. 1B, there is shown another depiction of the controlsystem 112. In various embodiments, the control system 112, may includea processor 150, such as a known type of microprocessor, dedicatedsemiconductor processor chip, general purpose semiconductor processorchip, or similar device. The control system 112 may further include amemory or memory unit 160, coupled to the processor 150, where thememory unit 160 contains a flux control routine 162, as described below.The flux control routine 162 may be operative on the processor 150 tocontrol precursor flux or precursor flow in the system 100, as detailedbelow. In some embodiments, the flux control routine 162 may include anend-of-life processor 164, an excursion processor 166, and aclog-detection processor 168, a temperature control processor 170, and aflux calculation processor 172, where implementation of these processorsis described with respect to the embodiments discussed below.

The memory unit 160 may comprise an article of manufacture. In oneembodiment, the memory unit 160 may comprise any non-transitory computerreadable medium or machine readable medium, such as an optical, magneticor semiconductor storage. The storage medium may store various types ofcomputer executable instructions to implement one or more of logic flowsdescribed herein. Examples of a computer readable or machine-readablestorage medium may include any tangible media capable of storingelectronic data, including volatile memory or non-volatile memory,removable or non-removable memory, erasable or non-erasable memory,writeable or re-writeable memory, and so forth. Examples of computerexecutable instructions may include any suitable type of code, such assource code, compiled code, interpreted code, executable code, staticcode, dynamic code, object-oriented code, visual code, and the like. Theembodiments are not limited in this context.

The memory unit 160 may include a system database 180, includingparameters for operating the system 100. Exemplary parameters include,for example, a baseline ampoule side temperature and a baseline ampoulebottom temperature, where these parameters may be set as starting pointsfor control operations to be performed, such as for temperaturecompensation to be performed. Other parameters subject to control mayinclude flow rate as well as deposition time. Additional parameters,which parameters may also be stored in system database 180, may beemployed to assign limits to ensure the temperature of a process stayswithin a safe range. Among these parameters are ampoule side temperatureminimum, ampoule side temperature maximum, ampoule bottom temperatureminimum, ampoule bottom temperature maximum, hot chamber temperature,and precursor degradation temperature.

Turning now to FIG. 1C, there is shown a system 118 for chemicaldeposition, according to further embodiments of the disclosure. Thesystem 118 involves use of at multiple precursors, generally provided asa gaseous species to process chamber, referred to as deposition chamber110. The system 118 may operate similarly to system 100, while thesystem 118 includes a first ampoule 104A for a first precursor and asecond ampoule 104B for a second precursor. The control system 112 mayact to independently control the first ampoule 104A and the secondampoule 104B according to the principles detailed in the discussion tofollow. This configuration facilitates control of two differentprecursors where the different precursors may be used form differentcondensing species in a CVD or ALD process. In other embodiments, asystem, such as system 100 or system 118, may be coupled with a gas flowapparatus supplying a gaseous precursor from a gas source to adeposition chamber, such as NH₃ or H₂. As such, a CVD or ALD system mayemploy the gas source to deliver the gaseous precursor, while at leastone other precursor is delivered from an ampoule under active controlaccording the embodiments described herein.

In various embodiments, the sensor assembly 108 may be arranged with anysuitable components for monitoring a precursor, includingelectromagnetic radiation, acoustic signals, and so forth. Theembodiments are not limited in this context. The sensor assembly 108 maydetermine precursor flux or concentration by measuring a change insignal intensity of an appropriate signal transmitted through the sensorassembly 108, as detailed below. Turning to FIG. 2A and FIG. 2B, thereis shown principle of operation of the sensor assembly 108, inaccordance with some embodiments of the disclosure. The sensor assembly108 may include a light source 120, such as an infrared, visible, orultraviolet light source, and a detector 122, facing the light source120. The detector 122 may be any detector, appropriate for the type ofradiation source used for light source 120. The sensor assembly 108 mayfurther include a chamber, shown as cell 124, where the cell 124 isarranged to receive a precursor 126 and to conduct the precursor 126, asthe precursor 126 travels from the ampoule 104 to the deposition chamber110. When the precursor 126 is absent from the cell 124, as in FIG. 2A,the detector 122 may register a signal, such as the background signal130. The background signal 130 represents transmitted (detected)intensity as a function of wavelength of the radiation from light source120. In some embodiments, the background signal 130 may be featureless,such as shown in FIG. 3A. When precursor 126 is present in the cell 124,the precursor may absorb radiation emitted by the light source 120,wherein the detector 122 registers a precursor signal 134. For clarityof explanation, the precursor signal 134 is shown to exhibit a peak 136,while the precursor signal 134 may include a multiplicity of features,including multiple peaks in some embodiments. Notably, the presence ofthe precursor 126 in the cell 124 may reduce the overall intensity ofdetected radiation in precursor signal 134, as opposed to backgroundsignal 130. As detailed below, in various embodiments, the recording ofthe background signal 130, as well as the monitoring of the precursorsignal 134, over a plurality of instances, is employed to controloperation of a deposition process.

As further shown in FIGS. 3A and 3B the sensor assembly may also collecta reference signal 132, where the reference signal 132 indicates therelative changes inn detector performance of the detector 122 over time.Changes in intensity of the reference signal 132 may be indicative ofdegradation in performance of the detector 122. By collecting thereference signal 132 at various instances, in conjunction with measuringthe background signal 130, and precursor signal 134, the amount ofprecursor 126 may be accurately determined over time. In particular, thelight absorption by precursor 126 may be directly proportional to thepartial pressure of the precursor 126 in the cell 124. As such, physicalmodelling may be employed to calculate precursor flux at multipleinstances, based upon the repeated measurement of a precursor signal134, facilitating better control of chemical deposition processesinvolving the precursor 126. In addition to measuring precursor flux,the cell pressure, such as total pressure, in the cell 124 may also bemeasured.

Turning now to FIG. 4 there is shown a graphical depiction of variousoutputs of the control system 112, in accordance with embodiments of thedisclosure. The curve 402 illustrates temperature of the ampoule 104 asa function of time. In this example, the temperature is relativelyconstant as a function of time. During a deposition process, thechanging of temperature may result in the changing of precursor flux byheating the ampoule 104 to generate a higher partial pressure ofprecursor.

The curve 406 represents the reference intensity of a detector, forexample, indicating the detector continues to function the same over thetime period measured. The health of a sensor may be determined fromcomparison of a reference intensity value taken at a certain time, withrespect to the reference intensity at a current time. Thus, if the valueof the reference intensity deteriorates substantially over time, thisdeterioration may be deemed an indication of bad health of the sensor.The curve 408 represents the pressure in a chamber as a function oftime, while the curve 404 represents the concentration of a precursor asa function of time. As shown, the precursor is delivered in a series ofpulses of concentration 412, resulting in corresponding pulses ofpressure.

Turning now to FIG. 5 there is shown a curve 502, representing theprecursor flux transported through a system, such as the flux of aprecursor conducted through the sensor assembly 108. In accordance withvarious embodiments of the disclosure, a physics-based calculation isperformed to determine precursor flux, where the calculation does notrequire a constant pressure or temperature at a sensor, such as detector122, or within the gaslines used to conduct the precursor from anampoule to deposition chamber. In the example of FIG. 5, the curve 502exhibits a series of pulses 506, representing pulses in precursor flux,generated by pulses of the precursor. The curve 504 represents theintegrated flux of precursor over time, representing a sum of the pulses506. The curve 504 may be indicative of the amount of precursordelivered to a deposition chamber at any given instance in time. Asensor assembly, such as sensor assembly 108, may be maintained in anoperational state during the chemical deposition process, so any pulse506 is recorded, wherein the integrated flux at a given instancerepresents the sum of all the flux pulses recorded to that point.

While the example of FIG. 4 and FIG. 5 are directed to precursor fluxmonitoring, in other embodiments, byproducts or secondary precursors maybe monitored. For example, in some chemical systems, a precursor maydecompose during transport, wherein the precursor as well as thebyproduct of decomposition may pass through a detector cell.Accordingly, by adding an additional detector, so a precursor detector,byproduct detector, and health detector are present, such a detectorsystem may be used to determine relative flow of a precursor vs abyproduct.

The determination of precursor flux and integrated precursor flux may beused to monitor, characterize, or control a deposition process inaccordance with various embodiments of the disclosure. FIG. 6A, FIG. 6B,FIG. 6C, and FIG. 6D are exemplary graphs illustrating the relationshipbetween integrated flux or related entities and certain experimental oroperating parameters of a system, such as the system 100. The data shownrepresent the deposition of Cobalt using a (3,3-Dimethyl-1-butyne)dicobalthexacarbonyl (CCTBA) precursor. This chemical system is merelyexemplary, and in other embodiments other metal organic or halogenspecies may be used to deposit cobalt, or other metal.

In FIG. 6A, there is shown the relationship between integrated flux anddeposition time, for measurement collected over a deposition time windowas shown. The integrated flux is determined using a sensor assembly asdescribed above. As shown, the integrated flux shows a good linear fitwith deposition time. FIG. 6B depicts the relationship between carriergas flow rate and integrated flux, again showing linear behavior over acarrier flow rate between 100 sccm and 400 sccm. FIG. 6C depicts therelationship between ampoule bottom temperature and integrated flux,again showing linear behavior over a temperature range between 32 C and38 C.

In FIG. 6D, there is shown the measured thickness of a deposit as afunction of flux, showing a linear relation for two different units(alpha and beta). The data toward the right represents data collectedtoward the beginning of the ampoule life while a decrease in flux anddeposit thickness occurs as the ampoule precursor material is consumed.

Thus, the data shown in FIGS. 6A-6D illustrate how integrated flux in achemical deposition system such as cobalt is sensitive to parametersincluding deposition time, carrier flow rate, and ampoule temperature.In other embodiments, dilution flow of any other flow to a processchamber, the number of deposition steps, or chamber pressure may bemodulated to control precursor flux.

In some embodiments, the information regarding precursor flux may beused to dynamically control a deposition process, for example, toachieve process stability and to prevent or counter drift in adeposition process. FIG. 7 illustrates integrated precursor fluxbehavior as a function of time for an atomic layer deposition system fordepositing TaN. The diamond symbols indicate integrated precursor fluxas a function of time where no temperature adjustment is performedduring a series of depositions, for up to approximately wafer 4500. Alower limit and an upper limit are shown by the horizontal dashed lines.As illustrated, the precursor flux when temperature is not adjustedremains generally between the upper limit and lower limit up toapproximately the instance of processing of wafer 1500, and decreasessubstantially below the lower limit at higher wafer numbers. Given theupper limit and lower limit may represent a target operating range, theresults illustrate the uncompensated flow of precursor is unable tomaintain the process within the target operating range above wafer 1500.The triangle symbols represent integrated precursor flux as a functionof time where temperature adjustment is performed during a series ofdepositions, in accordance with embodiments of the disclosure. In thisset of data, the temperature of a precursor ampoule may be adjusted inaccordance with procedures detailed below. As a result, the integratedflux is maintained over the entirety of a range measured (up to wafer3500).

Turning now to FIG. 8, there is shown a process flow 800, in accordancewith embodiments of the disclosure. The process flow 800 may beimplemented by the processors as described above, and as indicated inthe figure. Notably, some operations may be performed by more than oneprocessor. At block 802, an integrated precursor flux is set for a givendeposition process. A setpoint may be established, where the integratedflux is to be determined based upon measurements of a precursor using asensor assembly in accordance with the embodiments described above. Invarious embodiments, multiple parameters may be set or monitored. Forexample, a baseline ampoule side temperature and a baseline ampoulebottom temperature may be set as starting points for temperaturecompensation to be performed. Additional parameters may be employed toassign limits to ensure the temperature of a process stays within a saferange. Among these parameters are ampoule side temperature minimum,ampoule side temperature maximum, ampoule bottom temperature minimum,ampoule bottom temperature maximum, hot chamber temperature, andprecursor degradation temperature.

At block 804, a substrate or wafer is processed according to the givendeposition process. The flow proceeds to block 806, where an integratedchamber flux is calculated for the precursor, as represented, forexample, at curve 504. At block 808, a sensor such as the detector 122is checked to see if correct readings are being made and a baselinereading is correct. If a determination is made wherein the sensor needsadjusting the flow proceeds to block 810, where in one mode a signal issent to a user indicating the sensor needs adjusting, while in anothermode, an adjustment to the sensor is performed automatically. The flowthen returns to block 804. If, at block 808, the sensor does not needadjusting, the flow proceeds to block 812, where the integratedprecursor flux from block 806 is checked against fixed control limits.If the precursor flux indicates the process is under control or withincontrol limits, the flow proceeds to block 814, where no adjustment ismade to ampoule temperature. The flow then returns to block 804 where awafer is processed while not having adjusted ampoule temperature for theprecursor.

In some embodiments, as exemplified in process flow 800, two sets oflimits may be specified, such as fault limits and waring limits. When awarning limit is exceeded, this condition triggers a temperature update.Fault limits are broader, wherein when a fault limit is exceeded, thiscondition indicates something has changed in the system (not the gradualdrift expected over an ampoule lifetime) and additional action isrequired.

In the process flow 800, if, at block 812, a fault condition (fault bandcondition) is detected, the flow proceeds to block 816, where an ampouleidle time is checked. The flow then returns to block 814 if a firstwafer is being processed. If a first wafer is not being processed, theflow proceeds to block 818, where fault detection and classification isperformed. The flow then proceeds to block 820, where a notificationsignal is sent to notify a user an excursion has been detected. The flowmay then proceed to block 814. In different implementations, processingmay be stopped or a user notified while processing continues via block804.

If, at block 812, a warning band condition is determined, the flowproceeds to block 822, where an error calculation € is performed.

In different embodiments, warning and fault limits may be assigned by auser or alternatively may be calculated automatically in a softwareroutine. In some examples, the limits represent a given number ofstandard deviations from the mean of a sample set.

In particular, the error calculation at block 822 may involve controllimits, determined experimentally, based upon sensor noise and thicknesssensitivity. The error value calculated may be based upon a subtractionof the integrated flux from an upper control limit (UCL) or lowercontrol limit (LCL). The flow then proceeds to block 824.

At block 824, a temperature increment ΔT is determined. In oneembodiment, the temperature increment may be calculated based uponΔT=P*€+D*d€/dt+I*∫€/dt, where P, I and D are the proportional, integral,and derivative gains. In one instance, P, D, and I may be experimentallydetermined from tuning experiments. The flow then proceeds to block 826.

At block 826, the temperature increment, ΔT, is rounded to a nearestlevel, such as to the nearest 0.5° C. The flow then proceeds to block828, where new setpoints are calculated for side and bottom temperaturesof an ampoule, wherein T_(K)=T_(K-1)+ΔT, where T_(K) is the temperatureat time k, and T_(k-1) is the previous temperature setpoint. The flowthen proceeds to block 830.

At block 830, where the setpoints determined at block 828 are checkedagainst current temperature limits for the ampoule containing theprecursor. If, at block 830, the setpoints are within the limits, theflow then proceeds to block 832. These limits may include theaforementioned ampoule side temperature minimum, ampoule sidetemperature maximum, ampoule bottom temperature minimum, ampoule bottomtemperature maximum, hot chamber temperature, and precursor degradationtemperature.

At block 832, the ampoule temperature setpoints are updated based uponthe new setpoints determined at block 828. The flow then proceeds toblock 834 to wait for the precursor flux to stabilize, and then returnsto block 804.

If, at block 830, the setpoints are not within the limits, the flowproceeds to block 836, where the end of life of the precursor ampoule ischecked. At block 836, if a determination is made wherein the ampoule isat an end-of-ampoule life condition, the flow proceeds to block 838,where a signal is sent to notify a user for preventative maintenance.The flow then proceeds to block 840, where a temperature increment isrecalculated based upon a most conservative limit. The most conservativelimit may represent the lowest of the applicable maximum temperatures orhighest of the applicable minimum temperatures. The flow then returns toblock 828. If, at block 836, a determination is made wherein the ampouleis not at end of life, the flow proceeds directly to block 840. Theend-of-life determination may be made based upon when temperaturecompensation is no longer able to maintain a deposition process withinacceptable process conditions.

Turning now to FIG. 9A there is shown a process flow 900 according toadditional embodiments of the disclosure. The process flow 900 may beimplemented by the clog-detection processor 168, and may be used todetermine the presence of clogs and clog location within a deliverysystem for chemical deposition. A model delivery system 930, includingprecursor ampoule 932 and sensor assembly 934, are shown in block formin FIG. 9B. Turning to process flow 900, at block 902, a determinationis made as to whether a transducer pressure in a gasline delivering aprecursor is too high. The transducer pressure may be measured justdownstream of a carrier mass flow controller in the gas line. Anindication of “too high” may be determined statistically. A set of“good” recipes may be employed to determine the expected mean andstandard deviation (sigma), wherein a deviation on the order of 3 sigmais used to determine if the pressure is high (depending on sample sizeand acceptable confidence level). If not, the flow proceeds to block904, indicating no clog in a gasline is detected. If, at block 902, thetransducer pressure is high, the flow proceeds to block 906, where adetermination is made if the sensor assembly 934 pressure is too high.If so, the flow proceeds to block 908, where a signal is sent indicatinga clog is detected downstream of the sensor assembly 934. If thepressure is not too high in the sensor assembly 934, the flow proceedsto block 910.

At block 910, a determination is made if the transducer pressure is highin a bypass mode, shown by position 4 in FIG. 9B. If not, the flowproceeds to block 912 where a determination is made as to whetherprecursor flux is low. The determination of whether the precursor fluxis low may be made by measuring the precursor flux at the sensorassembly 934. In particular examples, the measured precursor flux iscompared to “good” data using statistical approaches including mean andstandard deviation. If, at block 912, the precursor flux is not low, theflow proceeds to block 914, where a signal is sent indicating a clogexists at the precursor ampoule 932 inlet, as shown by position 2. If,at block 912, the precursor flux is determined to be low, then the flowproceeds to block 916, where a signal is sent to indicate a clog ispresent at the precursor ampoule 932 outlet, as indicated by position 3.

If, at block 910, a determination is made wherein the transducerpressure is high in bypass mode, the flow proceeds to block 918, where adetermination is made as to whether the precursor flux is low. If not,the flow proceeds to block 920, where a signal is generated indicating aclog exists upstream of the precursor ampoule 932 inlet, as indicated byposition 1. If so, the flow proceeds to block 922, where a signal issent indicating a clog between the precursor ampoule 932 outlet andsensor assembly 934, as indicated by position 4.

In sum, the present embodiments provide the advantages of the ability todetermine precursor flux during operation of a chemical depositionsystem, to determine such changes in precursor flux in real time, todynamically adjust operating parameters such as ampoule temperature inreal time, in order to maintain precursor flow within acceptable limits.Other advantages include the ability to determine or predict end-of-lifeof a precursor ampoule so replacement need not take place beforecorrections cannot be made to maintain the precursor flow within limits.Further advantages include the ability to determine the presence ofclogs in multiple different locations of a precursor delivery system.

The present disclosure is not to be limited in scope by the specificembodiments described herein. Indeed, other various embodiments of andmodifications to the present disclosure, in addition to those describedherein, will be apparent to those of ordinary skill in the art from theforegoing description and accompanying drawings. Thus, such otherembodiments and modifications are intended to fall within the scope ofthe present disclosure. Furthermore, the present disclosure has beendescribed herein in the context of a particular implementation in aparticular environment for a particular purpose. Those of ordinary skillin the art will recognize the usefulness is not limited thereto and thepresent disclosure may be beneficially implemented in any number ofenvironments for any number of purposes. Thus, the claims set forthbelow are to be construed in view of the full breadth and spirit of thepresent disclosure as described herein.

What is claimed is:
 1. An apparatus for controlling precursor flow,comprising: an ampoule to output a precursor; a sensor assemblycommunicatively coupled to the source, and comprising: a cell, coupledto the source, to receive and conduct the precursor; a detector, todetect light transmitted through the cell; and a control system, thecontrol system arranged to determine a precursor flux value based upon achange in detected light intensity received from the cell during flow ofthe precursor through the cell, the control system comprising: atemperature control processor, configured to: determine a flux errorvalue based upon the precursor flux value; determine a temperatureadjustment ΔT, based upon the flux error value; and calculate a new setof temperature setpoints to be applied to the ampoule; and anend-of-life processor, the end-of-life processor configured to: checkfor an end-of ampoule-life condition when the new set of temperaturesetpoints is not within the predetermined set of temperature limits. 2.The apparatus of claim 1, comprising a flux calculation processor todetermine the precursor flux value by: receiving a first referencesignal in the cell, generated at a first instance, the first referencesignal indicative of a detector performance at the first instance for adetector, the detector to detect a light intensity from a light source;receiving a background signal, generated at the first instance, thebackground signal being generated by the detector; receiving a secondreference signal, generated at a second instance, subsequent to thefirst instance, the second reference signal indicative of the detectorperformance at the second instance for the detector; and receiving aprecursor signal, generated at a third instance, subsequent to the firstinstance, when the precursor is flowing in the cell.
 3. The apparatus ofclaim 1, the temperature control processor configured to: determine awarning band condition based upon the precursor flux value; and adjust atemperature of the ampoule based upon the warning band condition.
 4. Theapparatus of claim 1, the flux calculation processor configured tocalculate an integrated flux of the precursor by determining theprecursor flux value at a plurality of instances.
 5. The apparatus ofclaim 1, the temperature control processor configured to adjust thetemperature by: determining a temperature adjustment ΔT, whereΔT=P*€+D*d€/dt+I*∫€/dt, where P, I and D are a proportional, integral,and derivative gains, and where € is an error based upon currenttemperature limits of the ampoule.
 6. The apparatus of claim 1 thetemperature control processor configured to adjust a temperature of theampoule by: applying the new set of temperature setpoints to controlheating of the ampoule when the new set of temperature setpoints arewithin a predetermined set of temperature limits.
 7. The apparatus ofclaim 1, the end-of-life processor configured to: recalculate ΔT togenerate a conservative ΔT based upon a most conservative limit when theend-of ampoule life condition has not been met; and calculate the newset of temperature setpoints to be applied to the ampoule based upon theconservative ΔT.
 8. The apparatus of claim 1, the flux control routinefurther comprising an excursion processor, the excursion processorconfigured to: determine a fault condition based upon the precursor fluxvalue; and send a notification signal of an excursion, when a substratebeing processed is during the fault condition is not a first substrate.9. The apparatus of claim 1, the flux control routine further comprisinga clog detection processor, the clog detection processor configured to:receive a cell pressure reading for the cell; receive the precursor fluxvalue; and determine a clog location based upon the cell pressurereading and precursor flux value.
 10. A method of controlling precursorflow, comprising: measuring a change in detected signal intensity in acell of the gas delivery system, caused by the flow of a precursor;determining a precursor flux value based upon the change in the detectedsignal intensity; determining a flux error value based upon theprecursor flux value; calculating a new set of temperature setpoints tobe applied to the ampoule; and checking for an end-of ampoule-lifecondition when the new set of temperature setpoints is not within apredetermined set of temperature limits.
 11. The method of claim 10,wherein the measuring the change comprises: receiving a first referencesignal in the cell at a first instance, the first reference signalindicative of a detector performance at the first instance for adetector, the detector to detect a light intensity from a light source;receiving a background signal at the first instance, the backgroundsignal being generated by the detector; receiving a second referencesignal at a second instance, subsequent to the first instance, thesecond reference signal indicative of the detector performance at thesecond instance for the detector; and receiving a precursor signal fromthe detector at a third instance, subsequent to the first instance, whenthe precursor is flowing in the cell and light is generated by the lightsource.
 12. The method of claim 10, wherein the providing the flow ofthe precursor comprises providing a plurality of pulses at a pluralityof instances of the precursor, the method further comprising calculatingan integrated flux of the precursor based upon determining the precursorflux value at the plurality of instances.
 13. The method of claim 10,further comprising: determining a warning band condition based upon theprecursor flux value; and adjusting a temperature of the ampoule basedupon the warning band condition.
 14. The method of claim 13, wherein theadjusting the temperature comprises: determining a temperatureadjustment ΔT, where ΔT=P*€+D*d€/dt+I*∫€/dt, where P, I and D are aproportional, integral, and derivative gains, and where € is an errorbased upon current temperature limits of the ampoule.
 15. The method ofclaim 13, wherein the adjusting the temperature comprises: applying thenew set of temperature setpoints to control heating of the ampoule whenthe new set of temperature setpoints are within the predetermined set oftemperature limits.
 16. The method of claim 15, wherein the adjustingthe temperature comprises: recalculating ΔT to generate a conservativeΔT based upon a most conservative limit when the end-of ampoule lifecondition has not been met; and calculating the new set of temperaturesetpoints to be applied to the ampoule based upon the conservative ΔT.17. The method of claim 10, further comprising: determining a faultcondition based upon the precursor flux value; and sending anotification signal of an excursion, when a substrate being processed isduring the fault condition is not a first substrate.
 18. A method,comprising: determining a precursor flux value based upon a change indetected signal intensity received from a cell of a gas delivery systemto deliver a precursor; determining a flux error value based upon theprecursor flux value; determining a temperature adjustment ΔT, basedupon the flux error value; calculating a new set of temperaturesetpoints to be applied to the ampoule; and checking for an end-ofampoule-life condition when the new set of temperature setpoints is notwithin the predetermined set of temperature limits.
 19. The method ofclaim 18, comprising determining the precursor flux value by: receivinga first reference signal in the cell, generated at a first instance, thefirst reference signal indicative of a detector performance at the firstinstance for a detector, the detector to detect a light intensity from alight source; receiving a background signal, generated at the firstinstance, the background signal being generated by the detector;receiving a second reference signal, generated at a second instance,subsequent to the first instance, the second reference signal indicativeof the detector performance at the second instance for the detector; andreceiving a precursor signal, generated at a third instance, subsequentto the first instance, when the precursor is flowing in the cell. 20.The method of claim 18, further comprising: applying the new set oftemperature setpoints to control heating of the ampoule when the new setof temperature setpoints are within a predetermined set of temperaturelimits.